Snap-acting switch mechanisms



April 16,. 1957 R. HAPPE 2,789,172

SNAP-ACTING SWITCH MECHANISMS 2 Sheets-Sheet 1 Filed May 26, 1953 April16, 1957 R. HAPPE SNAP-ACTING SWITCH MECHANISMS 2 Sheets-Sheet 2 FiledMay 26, 1955 m. w n m nolo? Hajnlve ATTORNEY United States PatentSNAP-ACTIN G SWITCH MECHANISMS Reynold Happe, Pittstown, N. J., assignerto The Singer Manufacturing Company, Elizabeth, N. J., n corporation ofNew Jersey Application May 26, 1953, Serial No. 357,518

Claims. (Cl. 20G- 67) This invention relates to an electric switchmechanism and more particularly to one which provides a positive snapaction responsive to small actuating pressure.

An important object of this invention is `to provide a switch havingminimum dimensions relative lto its current-carrying capacity.

Another object of this invention is to provide a switch which hassubstantial contact movement responsive to minimum actuator movement.

A further object of this invention is to provide a sensitive snap-actionmechanism for a switch which effects, during normal operation, asubstantial contact wipe.

A still further object of .this invention is to provide apressure-sensitive switch which is characterized by having one of itsdimensions relatively very small, which creates a generally thin wafershape for the entire unit.

With the above and other objects in view, as will hereinafter appear,the invention comprises the devices, combinations, and arrangements ofparts hereinafter set forth and illustrated in the accompanying drawingsof a preferred embodiment of the invention, from which the severalfeatures of the invention and the advantages attained thereby will bereadily understood by those skilled in the art.

lIn the drawings:

Fig. l is an open plan view of a snap acting electric switch embodyingmy invention and showing one extreme position of the parts.

Fig. 2 is an open plan view similar to Fig. l but showing the otherextreme position of the parts.

Fig. 3 is a longitudinal section partly in elevation taken on line 3-3of Fig. 1 and includes the cover.

Fig. 4 is a partially disassembled view of the primary components of theswitch of Fig. l.

lFig. 5 is a detailed View showing a pivotal connection used in theswitch of Fig. l.

Pig. 6 is a perspective view showing the general external appearance ofthe switch of Fig. l.

Referring now to Fig. 1, a narrow, flexible band 10 made of at springstock, preferably of beryllium copper alloy, is secured -to a singlesupport 11 which, in turn, is secured to an insulation base 12. The band10 -is bent to form two spaced-apart limbs 13 and 14 which extend`generally in -the same direction from the stationary support 11. Thelimb 14 is relatively short and straight, while the other limb 13 islonger, bowed and positioned so that its free end 15 extends beyond andoverhangs the free end 16 of the shorter limb 14. A straight link 17 -issubstantially stiffer than the resilient limbs 13 and l14 and, as seenbest in Fig. 4, is formed at each end with reduced shouldered portions18 and 19, which are adapted to t within cooperating apertures 20 and 21in the limbs 13 and 14 respectively. These elements are shown assembledin Fig. 5. In this manner, the link 17 is suspended between andpivotally connected to each of the free ends of the limbs 13 and 14, andthe length and configuration of the limbs is such that the link 17 isalways under compression between said free ends;

vIn the preferred embodiment shown in Fig. l, the support 11 to whichthe band 10 is secured as by rivet 29, is bent to form a U-shapedelement having one limb 30 extending through the wall of the base 12 toprovide a soldering lug; and the other limb 31 is received in aninternal recess 32.

The bowed limb 13 terminates in -a sharply-bent contact arm portion 22to which may be secured a double contact button 23. This constitutes themovable contact which is coniined to operate between two spacedapartconducting iingers 24 and 25 which are each secured 4to the insulationbase 12 and extend Ythrough the wall thereof to form external solderinglugs. These tingers are provided with contact buttons 26 and 27respectively, and constitute the stationary contacts which may beconnected into external circuits, as desired.

lI1: will be seen in Fig. 4, which shows the limbs 13 and 14 in theirnormal unstressed condition, that the span distance between the freeends 15 and 16 lthereof is less than the seated length of the link 17,so that the link, when it is Iinserted to complete the loop, as in Fig.5, must be under compression. The amount of compression in the link 17depends upon its position relative to the limbs 13 and 14, and there isa position of maximum compression indicated by the dotted lines inPig. 1. This is an unstable condition and slight furthercounterclockwise angular movement of the link 17 reverses the forceacting on the bowed limb causing it and Ithe movable contact 23 to movewitha snap action to its yother engaging position, with the stationarycontact 27 as shown in Fig. 2. The limb 14 is formed so that, normally,it biases the link 17 to one side of its unstable position, as shown byfthe full lines in Fig. l. This corresponds to stable closure of thecontacts 23 and 26. A headed pin 28 of insulation material is mountedfor endwise movement in an -apertured portion 33 of a wal-l of the base12 and imparts movement to the limb 14 to swing the link 17 to andthrough its intermediate unstable posi-tion shown dotted, whence itsnaps to the second stable position shown in Fig. 2, in which case thecontacts 23 and 27 are closed. Upon release of the pin 2S, the biasingforce supplied by the limb 14 returns the switch to its normal position.

An insulated cover-plate 34, removably secured to th base 12 by screws35-35, completes the assembly enclosing the operative switch parts andserves to retain the elements 24, 25 and 30 in their properpredetermined positions in the wall slots to insure precise opera-tionof the switch. It will be noted that these elements are formed withnotched portions which engage with cooperating lugs in the slot portionsto prevent lateral displacement.

EIt will also be noted that neither end of the link 17 is tied to astationary pivot and, indeed, the link is allowed considerable freedomof endwise movement due to the resiliency in that direction provided bythe bowed portion of the limb 13. This structural relation results insubstantial wiping action between the contacts during normal operationof the switch which provides a continual cleaning of the contactsurfaces and the automatic maintenance of minimum contact resistance andmaximum useful life.

As a matter of fact, the exceptional wiping action of this switch makesit ordinarily unnecessary to use special precious metal contact materialsuch as would normally be used in the contact buttons 23, 26 and 27,thus decreasing substantially the manufacturing cost of the switchwithout sacrifice of its good operating characteristics. It will also benoted that, except for Ithe face-to-face contacts themselves, thecurrent path through the switch is entirely solid and continuous, and isnot Vbroken up by any of the joints of ythe usual pivoted elements whichwould contribute their resistance to the path and thus unduly limit thecurrent-carrying 'capacity of the switch. Y

It is also evident that the .basic mechanism of this switch .need besubstantially no wider than the narrow ba-nd. `10 from which the limbs13 and 14 are made. This is `due to the overhanging, .in-lineconstruction which eliminates the paralleled side-by-side springelements which characterize many of the prior-art snap switches. As aresult,'the general overall shape of the switch `takes on -the form of a.thin wafer as seen best in -F-ig. 6, and which .is a Very adaptableform and Vone which may readily be sandwiched vin-between existingequipment.

.Alfurther characteristic `feature of this construction permits themovable contact -23 to be moved in a direction precisely the oppositefrom that of the actuator pin 28 which imparts the movement.

Viewed in vits -broadest sense, the switch mechanism of thegpresentinvention comprises a closed, articulated loop supported at but onepoint `and comprising a U-shaped resilient leaf springr having ylimbs ofunequal length Withxa substantially stiff link pivotally securedVbetween the :free ends Vof said limbs and held in compressiontherebetween.

l.Having thus set `forth the nature of the invention, what I claimherein is:

1. In a snap-'acting switch, a single support, a spring supportedthereby -intermediate'its ends and bent to form two spaced-apart limbsof equal width and unequal length extending generally in the samedirection from the support, a link pivotally supportedin compressionbetween the free ends of said limbs, the longer one of said limbs beingbowed and formed at the end with a bent portion forming a movableelectrical contact arm, two jspaced tixed contacts, the shorter one ofsaid limbs being selectively movable-to impart la snap-action movementin said lmovable -contact arm between the positions thereof limited bysaid !fiXed contacts.

.2. In Y-afsnap-aoting switch, a single support, a single constant width`leaf spring supported vthereby'intermediate its yends land bent toform'two spaced Vapart limbs extending generally in the same ydirectionfrom the support, a .link vpivotally connected to and held .incompression between 'the free ends of said limbs, an actuator'V inoperative connection with one of Vsaid limbs, said other limb beingformed with -a bent terminal portion form-l ing a movable electricalcontact, and two, spaced, stationary Ycontacts defining `stableYpositionswbetween which said movable contact operates responsiveto-movement of said actuator.

3. In an electric switch, an insulated base, a conducting supportsecured to saidbase, a single piece of spring conducting material -ofconstant width secured to `said support and formed into two limbs whichextend in the same general direction from said support and terminate infree ends, a relatively stiff link element held suspended between saidfreefends in a pivotal connection therewith, a contact -arm formed asVan extension of one of said limbs, spaced contacts secured `to said baseand engageable by said contact arm, and manual means Yfor moving said`other limb to `impart snap-action to said -rst limb and to said Contactarm. Y

4. In a snapy switch, an insulated chaise, a support secured to saidbase, a single, flat, resilient leaf spring yof constant width 'bent `to4form a generally U-shaped member secured to said support adjacent thebend and positioned with its longitudinal axis parallel to said base,one limb being generally straight Vand short, the other limb Ybeingbowed, 4longer and extending more remotely from 'said support Vthan .thefree end of said first limb, a substantially stiliV 'link .pivotallysecured Vto and held Yin compression between Vthe free ends of saidYlimbs tofform a closed lloop with a single support, said Ybowed limbbeing formed with a terminal bend'providin'g 4a Contact arm, and twospaced conducting 'fingers secured .to said base lbetween which lingerssaid contact arm Vmoves to make and break contact therewith in responseto lienure o'f said iir'stliinb.V

5. In a snap-switch mechanism, a closed Yloop supported lat one Apointand comprising a generally U-shaped resilient leaf spring of constantwidth 'having one limb longer than the other, the longer limb beingbowed and bent at its free end to form a contact arm, a substantiallystitl:` link pivotally secured between the free end of -said shorter'limb `and the bend of said longer limb .and lheld in Ycompressiontherebetween by the normal spring .of the parts, two, spaced conductingelements forming stationary contacts between which said contact .armmoves, and an actua-tor -for iiexing said shorter limb to impartsnap-action to said longer limb and to said contact arm.

References Cited in the file of this patent UNIT-ED STATES PATENTS n Y`Holmes va Mar. 9, 1943V Hobbs Mar. t23,. lf954

